Radiant floor heating has been used for hundreds of years. The Romans were known to channel hot air under the floors of their villas, while the Koreans were known to channel hot flue gases under their floors before venting them up the chimney. In the 1930s, Frank Lloyd Wright designed many of his buildings with radiant floor heating.
There are three basic types of radiant floor heat, namely, radiant air floors where air is the heat carrying medium, electric radiant floors, and hydronic (liquid or hot water) radiant floors. All three types can be further subdivided by the type of installation: “wet” installations—those that make use of the large thermal mass of a concrete slab floor or lightweight concrete over a wooden subfloor, and “dry” installations—those in which the installer inserts the radiant floor tubing between two layers of plywood or attaches the tubing under the finished or subfloor.
Hydronic (liquid or hot water) radiant floor systems, which have been deemed the most popular and cost-effective systems for heating-dominated climates, pump heated liquid or water from a boiler through tubing laid in a pattern underneath the floor. The temperature in each room is controlled by regulating the flow of hot liquid or water through each tubing loop. This is done by a system of zoning valves or pumps and thermostats.
In terms of installation, dry floor installations have been gaining popularity over wet floor installations. This is due in part to the fact that dry floors are faster and less expensive to build.
As alluded to above, dry radiant floors may be prepared or fabricated by installing the tubing from above the floor, between two layers of subfloor. In these instances, the tubes are often in aluminum diffusers that spread the liquid or waters heat across the floor in order to heat the floor more evenly. The tubing and heat diffusers may be secured between furring strips (sleepers) which carry the weight of the new subfloor and finished floor surface.
Several companies have attempted to improve upon the heat diffusers used in dry installations. For example, U.S. Pat. No. 5,454,428 to Pickard et al. (the '428 patent) discloses an extruded aluminum radiant heat transfer plate having heat transfer side edges or fins and an elongated receptacle running the length of the extrusion for receiving and holding/confining plastic tubing. The elongated receptacle can take the form of a “C” that stands above the plane of the heat transfer fins, or the form of a “U”, the legs of which integrally connect to the fins.
As referenced in Cols. 1 to 2, lines 63 to 4, of the '428 patent, in either of the above-referenced configurations, the tubing-receiving channel is semicircular with the degree of wrap being on the order of 200°. The sides of the receptacle that lead into the channel are planar and acutely-sloped from the vertical at about 30°. The sloped sides of the receptacle serve as a guideway facilitating the positioning and insertion of the tubing into the channel.
The inner diameter of the tubing-receiving channel closely approximates the outer diameter of the plastic tubing. Moreover, the tubing-receiving channel is extruded to a thickness that prevents it from readily deforming. As such, the plastic tubing is reportedly deformed during insertion and held tightly within the receiving channel permitting heat transfer essentially by conduction.
The side fins are relatively thin-walled (e.g., 0.078 to 0.015 inches), while the thickness of the walls of the tubing receptacle are relatively thick (e.g., at least 0.060 inches). See Col. 3, lines 44 to 50, and Col. 5, lines 9 to 13, of the '428 patent.
The principal mode of heat transfer between the tubing and the channel wall in the '428 patent is one of conductance and not convection. See Col. 5, lines 44 to 47, of the '428 patent. This reference teaches that heat transfer by way of convection will result in deterioration of the heat transfer characteristics of the system. See Col. 5, lines 26 to 31, of the '428 patent.
U.S. Pat. No. 5,743,330 (the '330 patent) discloses panels for supporting heat transfer tubing that are touted as improvements over the hydronic radiant heat distribution panel and system of the '428 patent. The inventive panels basically comprise a track for receiving tubing carrying heat transfer fluid, which has an inner surface that is multi-faceted. The term “multi-faceted” is defined at Col. 3, lines 21 to 24, of the '330 patent as being “composed of a series of discontinuous, discrete, substantially straight faces 90 that are angled with respect to one another (FIGS. 1A and 2A).”
The segmented faces 90 of the multi-faceted, inner surface reportedly serve to securely grip the heat transfer tubing 17, thereby minimizing danger of the tubing 17 popping out or disengaging from the track 2 after installation, while providing for both convective and conductive heat transfer between the tubing 17 and receiving panel 1.
U.S. Patent Appl. Serial No. US 2005/0028966 A1 (the '966 patent application) discloses an improved heat distribution panel which utilizes an extruded tubing receptacle having a tube receiving channel for tightly gripping heat tubing throughout both straight and curved or looped runs. The tubing receptacle has a generally square or rectangular peripheral outline, which includes flat side wall and flat bottom surfaces. Heat tubing is received and retained by a snap-fit in the tube receiving channel of the tubing receptacle for heat transfer directly to the tubing receptacle essentially by conduction rather than convection. See page 1, paragraph [0008], of the '966 patent application. The channel portion of the receptacle may be constructed in accordance with the teachings of U.S. Pat. No. 5,454,428. See page 3, paragraph [0026], of the '966 patent application. Sheet metal heat transfer plates may be held against or permanently attached to the essentially planar outside surfaces of the tubing receptacle.
Unfortunately, tubing installed with the heat transfer plates or panels described above, which all employ top opening tubing receptacles for holding/confining plastic tubing, have been known to pop out or disengage from the receptacle after installation due to expansion and contraction of the tubing as liquid or water flowing there through changes temperature. Gravitational forces and/or vibrational stress encountered by the panels during system operation further promote this tendency of the tubing to disengage.
It is therefore a stated object of the present invention to address this deficiency and, in a preferred embodiment, to improve upon the radiant heat dissipation and cooling capacity and efficiency demonstrated by prior art radiant panels.